AudioService: handle BT profile disconnections

The BT A2DP, LE and HearingAid proxies to the BT service were
 initialized on profile connection, but were never reset on
 profile disconnection in BtHelper.
Wrapped the calls to the BT proxies with try/catch as the
 notification that a profile disconnected can happen while
 the proxy is used.

Bug: 269238085
Bug: 265815315
Test: BT crash case in bug
Change-Id: I77443a8b3afe8fd386401111e73f388e03510adb